Wittichenite, Cu3BiS3
Wittichenite (bluish grey), chalcopyrite (yellow needles),
covellite (blue) in bornite from Långban, Sweden.
Size 0.3 mm. Reflected
light, open nicols. The white mineral in the picture is native bismuth.
Photo © Kjell Gatedal, School of Mines and Metallurgy, Filipstad, Sweden